This invention relates to a photovoltaic-storage battery device and, more particularly, a photovoltaic-storage battery device which can serve as a driving power source for various low power consumption apparatus.
Recently, various devices which can convert solar radiation into electric or heat energy have been studied. Among these devices, solar batteries which make use of the photovoltaic effect are attracting attention as most promising products. Semiconductor materials for converting light energy into electric energy are also being extensively studied, and amorphous silicon which can be manufactured inexpensively and on a mass production scale is used for photoelectric films, the advent of amorphous silicon being the greatest technical innovation for increasing efficiency of use of the semiconductor materials. The amorphous silicon film can be formed on a glass substrate, for instance, by means of plasma CVD or glow discharge in an SiH.sub.4, B.sub.2 H.sub.6, or PH.sub.3 atmosphere. The substrate on which the amorphous silicon film is formed has been a transparent glass substrate or a thin stainless steel web with an insulating protective film formed on the surface. The stainless steel web is regarded as a promising substrate having flexibility.
However, when the solar battery having the construction as described above is used as a driving power source for a low power consumption device such as a desk calculator or a timepiece in a dark room without illumination, at night, or under the like conditions, it loses photovoltaic function and cannot operate, so that powering of the low power consumption device is prevented.